f/2.8 is not that thin DOF as you go to UWA. A 50 mm FL at 6 feet away f/2.8 gives DOF 0.78 ft (very thin, and difficult to manage), whereas a 24mm FL gives 3.4 feet, which is more than enough. At 15 feet away for a group, 24mm lens gives a whopping 36 feet of DOF. The razor thin concern doesn't apply at ultra wide.

An extreme example here: 24mm f/1.4 at 15 feet still has a DOF of 11 feet (but Canon's 24 1.4L is very soft in the corners at 1.4, different issue).

16mm f/2.8 at 6 feet away still has a very easy to manage DOF of 11 feet. Even as close as 3 feet, gives about 2 feet DOF.

So, f/2.8 really can help indoor photography for ultrawides without causing DOF problems.

yea. so f/2.8 can help isolate the subject from the background as well. in your example, the DOF extends from about 2 feet in front to 9 feet behind, which may be pushing it for subject isolation but still doable (you would more likely be stepping back and zooming in to 21 mm for example, for better results -- But to continue the example: at f/4 (still 16mm and subject distance of 6 feet) you loose almost all hope of subject isolation from the background because everything 34 feet behind the subject is in focus. so in this particular example, the f/2.8 lens has a hope of capturing a venue feature like a candelabra or whatever, with some isolation from the background, but the f/4 lens has little hope. I doubt very many people/group shots are taken at 16mm and 6 foot distance... but I'm not a wedding 'tog so I'm open to correction here

The things with weddings is that your often forced to shoot in less than ideal situations. I use the 24mm alot for family group shots --- why? it's a trade off...you want head to toe, but they want them in the church in front of the alter. If you slap the 50mm on, yes, less distortion but you have to step back so far that you get the pews in the shot, so your stuck doing a hip and up shot, or, go with the 24. Or if it's really tight and the bride and groom don't listen to me when i say it's better to do the shot outside (oh, it's too hot, or grandma is in the wheelchair, or any number of on the spot excuses that can happen) - yeah, go with the 16-35...it isn't ideal but that's wedding photography...

Not sure where this forum is heading but to bring it back to the 16-35 f4 IS.. Sounds good but I'd love to see it priced at a better prices point than the 16-35 f2.8. I love my photography and I know it's all about the money for Canon but they'd seriously sell more gear if they rejigged their price points.

...but f/2.8 in ultra wides is all about more light and nothing about shallow dof.

I'd have to disagree. With close subjects (albeit generally not people), I get shallow DoF with my 16-35/2.8, even at 16mm.

+1, a f2.8 wa definitely has a place in the lineup - with my 17-40L/4 you can get *some* bokeh (for me, usually light circles through leaves in the background) but I'd really like to have some more if possible. Focus stacking also solves the thin dof problem if shooting uwa macro, there are definitely creative possibilities here.

I hope all you people start selling your old, outdated 16-35L/2.8 lenses so I can buy one ... think of the horrible corner performance and sell before it's too late! :-)

...but f/2.8 in ultra wides is all about more light and nothing about shallow dof.

I'd have to disagree. With close subjects (albeit generally not people), I get shallow DoF with my 16-35/2.8, even at 16mm.

+1, a f2.8 wa definitely has a place in the lineup - with my 17-40L/4 you can get *some* bokeh (for me, usually light circles through leaves in the background) but I'd really like to have some more if possible. Focus stacking also solves the thin dof problem if shooting uwa macro, there are definitely creative possibilities here.

I hope all you people start selling your old, outdated 16-35L/2.8 lenses so I can buy one ... think of the horrible corner performance and sell before it's too late! :-)

Actually I did so yesterday and ordered the 16-35mm f/4 IS. The camerashop expects that soon more people will sell the f/2.8 version so the value price for occasion will drop. That is interesting for those who long for the f/2.8 version. I got a nice price.I found mine too soft in the corners. And, not using it much for indoor or evening events.

...but f/2.8 in ultra wides is all about more light and nothing about shallow dof.

I'd have to disagree. With close subjects (albeit generally not people), I get shallow DoF with my 16-35/2.8, even at 16mm.

You can force some bokeh out of almost any lens, some people even talk about bokeh on their 1/3" camcorders, but I don't see the point, it's not that impressive. I don't find it very impressive at 2.8 on a FF ultra-wide either, so I stopped trying on the 16-35. The 24 1.4 is the exception, you can get good bokeh relatively easily, and still have a lot of flexibility of composition. Anyway, my point was that shallow DOF is not the drawing card for UWA lenses, but everyone wants more light on the sensor.

Depending on the camera-motive-background distance relationship, f2.8 could make the difference between a usable and unusable "mobile-phone" infinity-dof style picture. Admittedly, you really need to be careful with the setup or the dof is too thin to be usable for higher export/print size.

...my point was that shallow DOF is not the drawing card for UWA lenses...

Not for you, but then, you're not 'everyone'.

Fine, if shallow DOF in ultrawide is your thing, have at it. But you'd get better results with a 24 1.4, than 2.8 zoom

In some situations a prime and/or 24mm focal length won't do, even for those who want a large aperture. In those scenarios a zoom covering the range which is as fast as is practical is the best option. f2.8 is still a whole stop up on f4. A whole stop in every respect, including the effects on DoF.

Fine, if shallow DOF in ultrawide is your thing, have at it. But you'd get better results with a 24 1.4, than 2.8 zoom

You're missing the point here :-). My photos aren't made by my lenses, but by me. For some situations, you need an uwa, you cannot move the wall behind you or elevate the motive if you're lying on the ground and shooting upwards.

Plus 16/17mm does have a very distinctive and interesting "non-p&s" look... even if it's not that much difference from a wide 24mm (whatever this is, for example the current 24-70L2's wide end is longer than 24-70L1 or Tamron).

Lol....UK pricing for the 16-35 f4 LIS seems to be nearly as expensive as the f2.8 version! While I'm sure the UK price will fall dramatically once the product is on the shelves, i really thing that canon urgently needs to refresh it's UK RRP policy.